A new NHTSA study, “Children Injured in Motor Vehicle Traffic Crashes,” analyzes the frequency of incapacitating crash injuries to children, as well as the most common types of injuries that occur. The research looks at children in three groups: under age 1, ages 1 to 3, and ages 4 to 7. The real-world data verify that significant injury is far more common among unrestrained children and in certain types of crashes, and that child restraints reduce the likelihood of incapacitating injury for all three age groups. The head was the most common region of injury for all children, but the type of head injury varied by age group, as did types of serious injury to other body regions.
The general findings of the report can be used to help parents understand the very real risk of injury in vehicle crashes and the value of using proper restraints. The data will also provide persuasive evidence for legislators who strive for occupant protection laws that are closer to best practice. The findings lend further verification that data do not support claims in some publications that question the value of CRs for older children (most recently SuperFreakonomics, see SRN Nov/Dec 2009).
For the portion of the study that sought to quantify the frequency of serious injuries, data from the National Automotive Sampling System (NASS, 1998-2008) was used. This data is drawn from police reports of crashes that include officer assessment of injuries and restraint use. Injury severity is recorded using a guideline referred to as “KABCO.” Investigating officers identify occupant injuries as K (killed), A (incapacitating injury), B (non-incapacitating injury), C (possible injury) or O (no injury). Although restraint use and general restraint type are reported, the available data did not allow this study to analyze the effect of potential CR misuse.
For NASS assessment, an “incapacitating injury” is defined as a nonfatal injury that prevents the injured person from continuing as normal the activities the person could perform before the injury occurred. Some of these injuries may have short-term effects; others, though not life-threatening, may require lifelong treatment. The study authors point out that children who suffer traumatic brain injuries can experience lasting or late-appearing neuropsychological problems.
Analysis of this data found that:
• Children riding in the vehicle front seats during frontal impacts were twice as likely
to sustain incapacitating injuries as those riding in rear rows.
• There was no significant injury difference between seating rows in rear impacts.
• Children riding in lap-shoulder belts were twice as likely to be seriously injured as
those riding in CRs.
• Rollover crashes were the most likely to cause incapacitating injuries, but incidence
rates were lowest for children riding in CRs.
• Injury incidence overall was significantly lower for children riding in CRs.
To be able to determine the frequency of crash-related injury by type, a different data source was used, the National Trauma Data Bank, a nationally representative sample of trauma centers. A sample of young crash victims from 2003-2007 was used to analyze the general body regions/types of injuries most commonly seen. Though this data provides desired insight into injury type, its use is limited in that it does not include specific crash-type data or child restraint information.
The National Trauma Data Bank collects injury data using the Abbreviated Injury Scale (AIS) to rate severity. Injuries to each body region are ranked on a scale of 1 to 6, with 1 being minor, 5 severe, and 6 unsurvivable. For this study, passengers under age 8 were analyzed when injuries were AIS 2 (moderate) or higher. (Although there is no direct relationship between KABCO and AIS, AIS 2+ injuries are likely to be coded as incapacitating injuries in the NASS General Estimates System.) Since, among those injured, the occurrence of multiple injuries to one or more body regions is common, the injuries with the highest AIS in each body region were used in this analysis.
For all injured children under age 8, the head was the most common body region to sustain AIS 2+ injuries, and among these, cerebrum injuries (contusions or lacerations) were the most common type. Concussion or unconsciousness was the most common type of head injury for children under age 1, while skull fractures were more common for older children. Head injury outcome can be worse for children than for adults, since some neurological deficits following head trauma may not manifest for many years and may impact the child’s development.
Abdominal injuries were common for all children, but the area of injury differed by age group. For infants under age 1, liver injuries were most common, followed by spleen. Injuries to the spleen were followed by those to the liver as most common in the age 1 to 3 category. And injuries to the small or large intestine were the most common type for children ages 4 to 7, followed by injuries to the spleen or liver.
Thoracic (chest) injuries were also quite common. Children under age 1 were more likely to sustain rib fractures, while children older than age 1 were more likely to sustain lung injuries. Spinal injuries were most common among infants under age 1, and lower extremity injuries were fairly consistent for all age groups.
The researchers concluded that incidence of incapacitating injuries is reduced by the use of CRs, and that this is true for all age groups studied and in all types of crashes. Although FMVSS 213 currently focuses only on frontal crash performance of CRs, field data shows that the devices are effective also in nonfrontal crashes. Based on real-world cases, unrestrained children in near-side impacts were eight times more likely to sustain serious injuries than those who rode in CRs or boosters. In rollover crashes, which are the most likely of all crash types to cause incapacitating injuries, the risk to unrestrained children is three times greater than to those in CRs. The study also demonstrates that serious injury risk is significantly lower for children riding in CRs as compared to those riding in vehicle seat belts, though naturally not to as great an extent as when compared to unrestrained children.
Additional data analysis and injury details are available in the full report, published in May 2010.